Speaking from memory here. Been a while since I had one apart.

The cam dowel should be pointing toward 4 o'clock and so should the crank pulley key (engine is the right way up in this instance). To check this, if you were to hold a straight edge across the centrepoint of the cam and the centrepoint of the crank you will see that the cam dowel and crank pulley key also share this centreline.

So if you could imagine the dowel and the key lining up they would both be pointing toward 4 o'clock, the confirmation of this being that they all sit along that straight line across the four points.

Otherwise count the number of links between the bright links on your old chain and use a marker to mark your new chain, chuck it on there to confirm.

I hope that make sense, I can dig out an image if you need.